Fluorine-based surface modifiers are excellent in terms of, for example, leveling properties, wettability, permeability, anti-blocking properties, slipping properties, water-oil repellency, and stain resistant properties and hence are widely used as additives that are added to various paints, coating materials, and the like.
For example, a cured coating film formed by applying and curing an active-energy-ray-curable composition containing such a fluorine-based surface modifier exhibits excellent surface properties. However, there are problems in that the production line is contaminated and the stain resistant properties of the surface of the cured coating film are degraded because part of the fluorine-based surface modifier is easily separated or evaporated from the surface of the cured coating film by heating, wetting, exposure to a chemical agent such as an acid or an alkali, cleaning for removing stains, or the like.
As an additive that can suppress the separation from the surface of the cured coating film and impart high stain resistant properties to the surface of the cured coating film, there has been proposed a fluorine-containing curable resin that has a poly(perfluoroalkylene ether) chain and has a polymerizable group that can be polymerized with other components in an active-energy-ray-curable composition (e.g., refer to PTL 1). However, there is a problem in that such a fluorine-containing curable resin cannot exhibit sufficient stain resistant properties when curing is performed through irradiation with active energy rays in an air atmosphere (in the presence of oxygen). Specifically, the polymerization of the fluorine-containing curable resin is inhibited by oxygen, and thus the polymerization of the fluorine-containing curable resin with other polymerizable components in the active-energy-ray-curable composition does not sufficiently proceed when the curing is performed through irradiation with active energy rays in an air atmosphere (in the presence of oxygen). This poses a problem in that a poly(perfluoroalkylene ether) chain cannot be sufficiently fixed onto the surface of the cured coating film and sufficient stain resistant properties cannot be exhibited.
As a fluorine-containing curable resin that can impart high stain resistant properties to the surface of a cured coating film even when curing is performed through irradiation with active energy rays in an air atmosphere, there has been proposed, for example, a fluorine-containing curable resin having a poly(perfluoroalkylene ether) chain and a maleimide group in its resin structure (e.g., refer to PTL 2). The fluorine-containing curable resin proposed in PTL 2 achieves the above effect through the cross-linking reaction of the maleimide group. However, there is still a problem in that the stain resistant properties of a cured coating film of the active-energy-ray-curable composition containing the fluorine-containing curable resin described in PTL 2 as a surface modifier is degraded once stains attached are wiped off.
Accordingly, a surface modifier that exhibits high stain resistant properties even when curing is performed in an air atmosphere (in the presence of oxygen) and can maintain stain resistant properties of the surface of a cured coating film even after stains attached to the surface of the cured coating film are wiped off has been demanded.